Endothelin-1-induced vasoconstriction causes a significant increase in portal pressure of rat liver: localized constrictive effect on the distal segment of preterminal portal venules as revealed by light and electron microscopy and serial reconstruction

Intraportal infusion of endothelin-1 (ET-1), a potent vasoconstrictor, significantly elevates portal venous pressure. To determine the major site of vascular constriction in the intrahepatic porto-sinusoidal system, we performed an in situ perfusion of rat livers with 1 nmol/L ET-1 at a flow rate of 20 mL/min. Portal pressure rose from 22 cm H2O to 54 cm H2O within 25 minutes. Specimens were prepared for light-microscopic serial reconstruction and electron microscopy. The distal segment of preterminal portal venules (DS/PPV) with an inner diameter of 40 to 80 microm showed complete obliteration of the lumen over a 300-microm distance caused by the intense contraction of perivascular smooth muscle cells and protruding of endothelial cells into the lumen. The proximal segment of preterminal portal venules (PS/PPV) with a larger diameter up to 150 microm also underwent strong constriction, but still had luminal space for the flow, while the PS/PPV with a diameter of 150 to 400 microm showed moderate or mild constriction and retained a wide lumen. Neither terminal portal venules, inlet venules, sinusoids, nor central veins, however, exhibited demonstrable constriction. Liver parenchyma fed by the inlet venules that emerged from the PS/PPV exhibited a wide sinusoidal lumen and vacuolated hepatocytes caused by the influx of excess portal perfusate that escaped from the occlusive areas. The present study has revealed that the DS/PPV functions as a presinusoidal quasi-sphincter mechanism and is involved in the redistribution of intrahepatic portal flow under increased portal pressure.     

Increased polyploidy, delayed mitosis and reduced protein phosphatase-1 activity associated with excess copper in the Long Evans Cinnamon rat

Until now, it is not known whether copper hepatotoxicity impairs mitosis. Enlarged hepatocytes with huge nuclei considered as polyploids are frequently observed in the Long Evans Cinnamon (LEC) rat which exhibits an abnormal accumulation of hepatic copper due to a defect in the gene homologous to human Wilson's disease gene responsible for intracellular copper delivery. This defect may lead to a abnormal mitotic progression in increased polyploidization and is associated with excessive hepatic copper. This study was designed to examine whether excess copper impairs mitotic progression and results in increased polyploidization using a model of LEC rat liver. Polyploidy was analyzed by flow cytometry. The rate of mitotic progression was investigated using the fraction of mitotic hepatocytes or a mitosis-specific phosphoprotein retained in regeneration. Nuclear protein phosphatase-1 (PP-1) activity essential to mitotic progression was measured. The effect of excess copper on incidence of polyploidy, the rate of mitotic progression and nuclear PP-1 activity was investigated using age- or copper overload-dependent changes in them in LEC rat, or genetic profile-dependent changes of them in backcrosses. LEC rat liver showed an increase of polyploidy, a delay of mitotic progression, and a reduction of nuclear PP-1 activity. These abnormal features concurred with increase of copper concentration accompanied by changes of age in LEC rats from 2 to 4 months of age, induced by dietary copper overload in LEC rat, or caused by single genetic defect in backcrosses. Excess copper impairs mitotic progression, resulting in increased polyploidization. Nuclear PP-1 activity is likely to be at least one of targets of copper hepatotoxicity leading to impairment of mitotic progression.     

Stabilization of higher-order structure of poly(phenyleneethynylene)s by metathesis polymerization at the side chains

Novel poly(m-phenyleneethynlene-p-phenyleneethynylene)s bearing polymerizable diene or norbornene groups were synthesized by the Sonogashira–Hagihara coupling polymerization of the corresponding d-hydroxyphenylglycine-derived diiodo monomers with p-diethynylbenzene. These polymers exhibited strong Cotton effects derived from a predominantly one-handed helical conformation in CHCl₃ and tetrahydrofuran, but exhibited weak or no Cotton effects in N,N-dimethylformamide. The metathesis polymerization of the diene and norbornene moieties was performed at the side chains of the polymers under diluted conditions in the presence of a chain-transfer agent, if necessary. The reaction took place intramolecularly, which was confirmed by size exclusion chromatography (SEC) measurements. The polymers exhibited stronger Cotton effects even in polar media after the intramolecular crosslinking, which indicated stabilization of the predominantly one-handed helical structures.     

Structural properties of carbon materials from the electrochemical reduction of fluorinated naphthalene pitch

Synthesis of carbon materials from fluorinated naphthalene pitch has been carried out by means of electrochemical reduction. Structural and morphological properties of synthesized carbons were investigated using X-ray photoelectron spectrum (XPS), Raman scattering spectrum, X-ray diffraction measurements and scanning and transmission electron microscopy (SEM and TEM). Furthermore, a change in the structure of synthesized carbons with an electron beam irradiation was examined. The synthesized carbon has a disordered structure composed of fragments of the sp² hexagonal network, and also has lots of micro-voids. A carbyne-like structure was found only a little with the reduction of fluorinated naphthalene pitch by Raman spectra. A lot of ribbon-like graphite nanocrystal was formed by irradiation of an electron beam at a high temperature to the defluorinated carbon. Bending of a long ribbon-like crystal of graphite was often observed. Formation mechanism of graphite nanocrystals was discussed.     

Welding experiments of aluminium pipe by space GHTA welding in aircraft-borne simulated space environment

The gas hollow tungsten arc (GHTA) welding experiments on aluminum pipe were carried out in a simulated space environment using an aircraft. A vacuum chamber and welding machine for GHTA welding test were placed in the cabin of the aircraft and the 10^? 2 G gravity environment was produced by a parabolic flight of the aircraft. The square butt welding joints with non root gap on aluminum pipe were made by orbital welding in the vacuum chamber without wire filler metal using DC or DC-pulsed power supply under the 10^? 2 and 1 G gravity conditions. The welding phenomenon during the aluminum GHTA welding recorded in the high-speed video image was analysed and also the macrostructure and mechanical properties of butt weld joints were investigated. The welding experiments under simulated space environment showed that the DC-pulsed GHTA process could make the welding joints without the weld defects such as a lack of fusion, oxide film inclusion and spattering, though throat thickness decreased by the impulsive arc pressure of pulsed current. It was also clarified that the arc discharge phenomenon and melting characteristic at the molten pool surface during the DC-pulsed GHTA welding were insensitive to the gravity condition. However, the sagging weld metal made at 1 G gravity condition increases a little more than that welded under the 10^? 2 G gravity condition.     

Selective grinding of glass to remove resin for silicon-based photovoltaic panel recycling

Secondary grinding was investigated as a mean of liberating glass from locked particles of glass and resin obtained by the primary shredding from the silicon-based PV panels. Many previous studies on separating glass from resin have focused on chemical processes. However, a simple physical process—using an eccentric stirring mill to selectively grind the glass, separating the glass from the resin, and concentrating the glass into a narrower particle size group—resulted in successful liberation. Grinding rate analysis using the population balance model quantitatively confirmed that glass particles were more easily ground than resin particles and that locked particles were more easily ground than free particles. This is because the high specific gravity of the glass particles and the greater adhesiveness of the locked particles cause them to be located near the stirring blade of the mill. The selectivity of grinding became more significant and the grinding time shorter as the rotation speed increased. At the optimal grinding speed of 2500 rpm, 97% of the glass was concentrated into particles under 5.6 mm in size in 5 min. The resulting glass particles had a carbon content of 1% or less, which makes them suitable for the manufacture of glass fiber.     

Lyapunov recursive design of robust adaptive tracking control with L 2-gain performance for electrically-driven robot manipulators

This paper develops a new Lyapunov recursive design for the tracking control problem of rigid-link electrically-driven robot manipulators with uncertainty by taking a tracking performance into account. The tracking performance is evaluated by L ₂-gain from a torque level disturbance signal to a penalty signal for the tracking error between outputs of the manipulator and desired trajectories. The novelty of our approach is in the strategy to construct such a Lyapunov function recursively that ensures not only stability of a tracking error system but also an L ₂-gain constraint, which provides a closed-form solution for non-linear H     

Selective incorporation of Si along step edges during delta-doping on MOVPE-grown GaAs (001) vicinal surfaces

We investigated the delta-doping (δ-doping) of Si using SiH₄ on MOVPE-grown GaAs (001) vicinal surfaces to explore the possibility of selective incorporation of Si along atomic steps, and to demonstrate doping quantum wires by the combination of multiatomic steps and wire-like doping. It was found that the doping density on vicinal surfaces was enhanced as the misorientation angle was increased, which suggested the enhanced decomposition of SiH₄ and the selective incorporation of Si at step edges. It was also found that this selective incorporation could be enhanced by annealing the surface prior to the δ-doping, which resulted from the reduced incorporation of Si at the terrace regions. Anisotropic electron transport properties which are expected from the wire-like incorporation along step edges are also discussed.     

Detection of telomerase activity in oral lesions

We present a rare complication of pericardiectomy and the effective management thereof. A 67-year-old female with dyspnea and upper abdominal pain was received at our department upon referral. Chest roentgenogram and cardiac catheterization preceded a diagnosis of constrictive pericarditis. Pericardiectomy was performed subordinate to median sternotomy and left anterolateral thoracotomy. Extubation was carried out on day 2 but reintubation was necessitated on the same day as a result of progressive dyspnea. Chest roentgenogram revealed an atelectasis of the left lung. Fiberoptic bronchoscopy showed left main bronchial stenosis resulting from a pulsating external structure. A postoperative computed tomogram substantiated the stenotic left main bronchus between the dilated left pulmonary artery and the thoracic descending aorta. An expandable metallic stent for the treatment of this complication was selected over other invasive procedures. Two years of follow-up reveal no complications. Accordingly, an expandable metallic stent has demonstrated its effectiveness not only on bronchial stenosis due to malignancy or tuberculosis but on benign cases such as this as well.     

Enhanced expression of catalytic subunit isoform PP1 gamma 1 of protein phosphatase type 1 in malignant fibrous histiocytoma

The expression of the three catalytic subunits of protein phosphatase (PP) type 1 and 2A, PP1 alpha, PP1 gamma 1, and PP2AC, was examined in malignant fibrous histiocytoma using immunohistochemical analysis. The percentage of cells stained positively with antiserum against PP1 catalytic subunit isoform PP1 gamma 1 was significantly higher in tumorous region than in non-tumorous region of malignant fibrous histiocytoma. Furthermore, tumorous region showed markedly high S-phase fraction in the cell cycle, as compared to non-tumorous region. These results suggest that PP1 gamma 1 is involved in the accelerated growth of tumor cells in malignant fibrous histiocytoma.